Cyrtoptychoceras undulatus Forbes 1846 from: Kennedy, W.J..Henderson, R.A.. (1992): Heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India . Palaeontology Vol. 35 p. 693-731 | . |
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Species Cyrtoptychoceras undulatus Forbes 1846 |
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| Diagnosis / Definition: |
Kennedy & Henderson (1992):
DESCRIPTION.-
The lectotype (Pl. 4, figs. 4-6, 8, 9, 11) is an incomplete body chamber 46 mm long, with the adult aperture preserved. The greater part of the specimen is slightly curved, curvature increasing towards the adult aperture, with the venter convex and dorsum concave in profile. The whorl section is circular, and expands very slowly. Ornament is of low, broad, blunt ribs, as wide as, or narrower than the interspaces. The ribs are transverse on the dorsum, feebly prorsiradiate on the flanks, and somewhat strengthened and transverse on the venter. The rib index is 2.
The whorl expansion rate increased markedly on the final sector, before the aperture and ornament is lost, leaving a 4 mm smooth section of shell, which terminates at a broad, deep constriction, prorsiradiate on the flank, and transverse on the venter, with a narrow, sharp adapical collar-rib. Beyond the collar, there is a further sector of shell, preserved on the ventral and ventrolateral regions only. It bears a series of weak riblets, the terminal one defining a broad linguoid ventral apertural process (Pl. 4, figs. 4, 5, 8, 9), BMNH C51119 is a series of near-straight sections of body chamber (Pl. 4, fig. 3), BMNH C51124 (Pl. 5, fig. 1) shows the ventral ornament, BMNH C51123 (Pl. 4, fig. 10) may show that of the dorsum, but is very small. None of the specimens show the suture. |
| Discussion / Comments: |
Kennedy & Henderson (1992):
TYPES.-
Lectotype, here designated, is BMNH C51118, the original of Forbes (1846, pl. 10, fig. 6), GSC R10503. Paralectoypes are BMNH C51119, C51123 and C51124; paralectotypes BMNH C51121 (Pl. 4, fig. 2), BMNH C51122 (Pl. 1, fig. 11) and C51120 (Pl. 1, fig. 10) are Glyptoxoceras rugatum. All are from the Valudavur Formation of Pondicherry, south India (ex Kaye and Cunliffe Collection).
DISCUSSION.-
See undr genus.
OCCURRENCE.-
As for types. |
| Systematics: |
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Subordo Ancyloceratina
Superfamilia Turrilitaceae
Familia Diplomoceratidae
Subfamilia Polyptychoceratinae
Genus Cyrtoptychoceras
Species Cyrtoptychoceras undulatus
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| Synonym list: |
Kennedy & Henderson (1992):
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| References: |
Forbes,E.. (1846):
Report on the Cretaceous fossil invertebrates from southern India, collected by Mr. Kaye and Mr. Cunliffe . Transactions of the Geological Society of London Vol. 2(7) p. 97–174
d'Orbigny,A. (1850):
Prodrome de Paléontologie. Stratigraphique universelle des animaux mollusques & rayonnés faisant suitre au cours élémentaire de paléontologie et de géologie stratigraphique. , Cours Élémentaire de Paléontologie et de Géologie Stratigraphiques Vol. 2
Stoliczka,F.. (1866):
The fossil Cephalopoda of the Cretaceous rocks of southern India. Ammonitidae with revision of the Nautilidae etc. . Memoirs of the Geological Survey of India, (l), Palaeontologica Indica10-13 p. 155-216
Kossmat,F.. (1895):
Untersuchungen über die Südindische Kreideformation. Erster Theil . Beiträge zur Paläontologie Österreich-Ungarns und des Orient Vol. 9 p. 97-203
Phillips,D.. (1977):
Catalogue of the type andjigured specimens of Mesozoic Ammonoidea in the British Museum (Natural History). , Trustees of the British Museum (Natural History) p. 220 pp.
Kennedy,W.J.. and Henderson,R.A.. (1992):
Heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India . Palaeontology Vol. 35 p. 693-731
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